Your first backup

The first time you back up your Mac with Time Machine, it might take a long time to complete. This is because Time Machine copies most or all of the data on your Mac to your first backup. You can keep using your Mac while Time Machine works in the background to back up your data.

After the first backup is complete, Time Machine works in the background to back up only files that have changed since your last backup. This means your next backup is usually faster.

If you want to pause a backup and finish it later, select Skip This Backup from the Time Machine menu. Time Machine automatically tries backing up again later. If you want to start a backup manually, choose Back Up Now from the menu.

Backing up large changes

Some backups might take longer than others if you've made changes to a lot of files, or changes to large files since the last time you backed up. You might see ”Preparing” in the Time Machine menu for a longer period of time when this happens. For example:

When your backup disk isn't available (such as when you're traveling, or your backup disk is disconnected or powered off) Time Machine can't back up your files. If you use your Mac for several days without access to your backup drive, it might take longer the next time the drive is available.

If you're using virtualization software on your computer, such as Parallels or VMWare, that software might create a large disk image or other file to store data related to other operating systems. Time Machine might try to back up the whole disk image, even if you've only changed a few files on it. For best results, make sure your software is up to date, then check the developer's support site for information on using Time Machine with these apps. If you want Time Machine to skip these files, you can also tell Time Machine to exclude them from your backup.

If you recently installed new software or upgraded macOS, it might take longer to complete the next backup. After Time Machine finishes backing up your new software, backups should be faster.

If you canceled or unexpectedly interrupted the previous backup, Time Machine might take longer the next time it backs up your files. This can also happen if you don't shut down your Mac properly, or if you don't eject a drive before disconnecting it.

Network speed

If you're backing up over a Wi-Fi network, make sure your Wi-Fi access point or router is nearby. A Wi-Fi network connection can slow down if your Mac is too far away from your router. You can get a good idea of how strong your wireless network signal is by looking at the Wi-Fi menu. If necessary, check for Wi-Fi issues.

Antivirus software

If you use antivirus software on your Mac, make sure that software is up to date. If it appears to interfere with backing up your computer, you might want to exclude your backup drive from the virus scan. Check the documentation that came with your antivirus utility or contact the maker of the utility for more information.

Check your drives

Your backup might be slower if there's an issue with one of the drives you're backing up, or with the drive where your backup is stored.

If you're using an AirPort Time Capsule, you can make it verify its built-in disk drive:

Disconnect your AirPort Time Capsule from AC power.

Wait ten seconds, then reconnect your AirPort Time Capsule to power.

When the built-in drive on your Time Capsule is working, the indicator light on the Time Capsule turns green. If there's an issue, the light flashes amber. Open AirPort Utility and connect to your Time Capsule to learn more about the issue. If you can't resolve the issue, you might need to erase the drive using AirPort Utility, after creating an additional backup using Time Machine and another drive. If you can't erase the drive, your Time Capsule might need service.

For other drives, open Time Machine preferences and turn Time Machine off, then use Disk Utility to verify your startup disk, external backup drives, and any other drives that you're backing up. You can turn Time Machine back on after your drives are verified or repaired successfully.

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